Method for manufacturing a mold for molding a seal member

Abstract

To provide a manufacturing method of a molding metal mold of a seal member which is excellent in a surface shape property, and can improve processability, and the seal member.SOLUTION: A manufacturing method of a molding metal mold 1 of a seal member molds the annular seal member having an internal peripheral side face and external peripheral side face. The molding metal mold comprises a pair of molding molds 2, 3 which are halved by mold halving faces 2a, 3a. The manufacturing method comprises an irregular face processing step of processing at least either of side faces of the internal peripheral side face and the external peripheral side face into an irregular face in at least either of the pair of molding molds, and a glossy surface processing step of cutting the other side face adjoining the irregular face which is processed by the irregular face processing step to a glossy face.SELECTED DRAWING: Figure 1B

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a mold for molding a sealing member. By law Regarding. [Background technology]

[0002] A known brake fluid pressure control device for vehicles such as automobiles includes a piston pump. The piston pump includes a drive member, such as an eccentric cam, and a piston (also called a plunger) that reciprocates within a cylinder chamber in response to the movement of the drive member. In this piston pump, a seal member is interposed between the cylinder chamber and the piston, and this seal member separates (seals) the pump chamber from the cam chamber.

[0003] If the outer surface of the seal member were to slide against the inner surface of the cylinder chamber, this could affect the increase in brake fluid pressure in the pump chamber. Therefore, it is preferable to make the inner side surface lower in friction than the outer side surface, and therefore the seal member preferably has a surface property such as a glossy surface that makes it difficult for the outer surface to slide against the cylinder chamber. On the other hand, it is preferable that the seal member have a surface property such as an uneven surface that has low friction and low adhesion so that the inner surface can slide against the piston.

[0004] Conventionally, as a technique for forming a surface texture such as an uneven surface, a technique for forming an uneven surface to a depth of 1 to 30 μm on the surface of a sealing member is known (see, for example, Patent Document 1). Also known is a technique for forming a surface texture such as an uneven surface by roughening the molding surface of a molding die by blasting or the like (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4940519 [Patent Document 2] Special Publication No. 2-1619 Summary of the Invention [Problem to be solved by the invention]

[0006] When forming a textured surface and a glossy surface on a sealing member, it is necessary to process the molding die to separate areas where the textured surface is to be formed from areas where it is not to be formed.

[0007] The present invention relates to a method for manufacturing a mold for molding a sealing member that has excellent surface properties and can improve processability. The law The objective is to provide [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the manufacturing method of a mold for molding a sealing member of the present invention is a manufacturing method of a molding mold for molding an annular sealing member having an inner peripheral side surface and an outer peripheral side surface. The molding mold has a pair of molding dies separated by a parting surface, and at least one of the pair of molding dies has a parting surface. Cutting is performed on the At least one of the inner peripheral side surface and the outer peripheral side surface forming a first molding surface corresponding to one of the first and second molding surfaces, and forming a preliminary molding surface which is a preliminary step for forming a second molding surface corresponding to the other of the first and second molding surfaces; a concave-convex surface processing step for processing a surface into a concave-convex surface; and the preforming surface and a glossy surface processing step of cutting the sheet to a glossy surface.

[0009] According to the present invention, the processing in the uneven surface processing step and the cutting in the glossy surface processing step are carried out for each mold, so that the processing can be carried out regardless of the position of the mold parting. Furthermore, since the textured surface and the glossy surface can be easily formed, there is no risk of variations occurring even when multiple pieces are molded using one molding die, and the sealing member can be molded cheaply and easily.

[0010] It is also preferable that the glossy surface processing step is carried out after the uneven surface processing step, and that part of the uneven surface processed in the uneven surface processing step is machined into a glossy surface. In this configuration, an uneven surface is formed on the mold in the uneven surface processing step, and then a glossy surface is formed by further cutting part of the uneven surface in the glossy surface processing step, so that the uneven surface and glossy surface can be formed without applying masking or the like to the molding surface.

[0011] It is also preferable that the uneven surface be left on the inner peripheral side of the molding surface of the mold. In this configuration, the outer periphery, which has a large molding surface area, is machined in the glossy surface processing step, which makes the machining easy and allows the molding die to be manufactured easily. Furthermore, the seal member molded by such a molding die can be suitably used in, for example, a piston pump having a piston that reciprocates within a cylinder chamber. In this case, the sliding of the piston can be ensured by the sliding contact of the inner peripheral side surface of the seal member, while the movement of the seal member relative to the cylinder chamber can be suppressed by the abutment of the outer peripheral side surface of the seal member.

[0012] The uneven surface processing step preferably includes processing the uneven surface by a blasting method. In this configuration, the uneven surface can be easily formed, thereby reducing costs. [Effects of the Invention]

[0019] Method for manufacturing a mold for molding a seal member according to the present invention By law This allows for excellent surface properties and improved processability. [Brief explanation of the drawings]

[0020] [Figure 1A] 1 is a perspective view showing a lower mold of a molding die manufactured by a method for manufacturing a molding die for a sealing member according to a first embodiment of the present invention. [Figure 1B] 1 is a cross-sectional view showing a molding surface of a molding die manufactured by a method for manufacturing a molding die for a seal member according to a first embodiment of the present invention. [Figure 2]FIG. 2 is a perspective view illustrating a lower mold of the molding die on which a concave-convex surface has been formed by a concave-convex surface processing step, illustrating a manufacturing procedure for the molding die for the sealing member according to the first embodiment of the present invention. [Figure 3] FIG. 2 is a diagram illustrating a manufacturing procedure for a mold for molding a seal member according to a first embodiment of the present invention, and is a perspective view showing a lower mold of the mold in the middle of forming a glossy surface by a glossy surface processing step. [Figure 4] 1 is a cross-sectional view of a seal member molded by a mold for molding a seal member according to a first embodiment of the present invention. [Figure 5] 1 is a cross-sectional view showing a piston pump using a seal member molded by a mold for molding a seal member according to a first embodiment of the present invention. [Figure 6A] FIG. 6 is a cross-sectional view showing a molding surface of a molding die manufactured by a method for manufacturing a molding die for a seal member according to a second embodiment of the present invention. [Figure 6B] FIG. 6 is a cross-sectional view showing a seal member molded by a mold for molding a seal member according to a second embodiment of the present invention. [Figure 7A] FIG. 10 is a cross-sectional view showing a molding surface of a molding die manufactured by a method for manufacturing a molding die for a seal member according to a third embodiment of the present invention. [Figure 7B] FIG. 10 is a cross-sectional view showing a seal member molded by a mold for molding a seal member according to a third embodiment of the present invention. [Figure 8A] FIG. 10 is a cross-sectional view showing a molding surface of a molding die manufactured by a method for manufacturing a molding die for a seal member according to a fourth embodiment of the present invention. [Figure 8B] FIG. 10 is a cross-sectional view showing a seal member molded by a mold for molding a seal member according to a fourth embodiment of the present invention. [Figure 9A] FIG. 10 is a cross-sectional view showing a molding surface of a molding die manufactured by a method for manufacturing a molding die for a seal member according to a fifth embodiment of the present invention. [Figure 9B] FIG. 10 is a cross-sectional view showing a seal member molded by a mold for molding a seal member according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same elements are designated by the same reference numerals, and duplicated descriptions will be omitted.

[0022] (First embodiment) As shown in FIG. 1B, the mold 1 for molding the seal member of this embodiment is composed of a pair of upper and lower molds (upper mold 2 and lower mold 3). The upper mold 2 and lower mold 3 are separated by a centrally parted (centered) parting surface (parting line, mold parting surface) 2a, 3a, which is approximately in the center in the vertical direction. The molding mold 1 is a mold for compression molding the seal member 50 shown in FIG. 4, and has a molding surface with a substantially X-shaped cross section. The molding surfaces of the upper mold 2 and lower mold 3 have cross-sectional shapes that are approximately symmetrical from top to bottom. First, the lower mold 3 will be described in detail.

[0023] 1A and 1B, the lower mold 3 has an inner peripheral molding surface 32 and an outer peripheral molding surface 33 that is continuous with the inner peripheral molding surface 32. The inner peripheral molding surface 32 and the outer peripheral molding surface 33 have a curved, concave cross-sectional shape and are provided with grooves 31, 31 in the portions facing the parting surface 3a. The grooves 31, 31 function as spaces for forming overflow portions 55a, 55a of the seal member 50 (see FIG. 4).

[0024] The inner peripheral molding surface 32 is a surface formed on the radially inner side of the lower mold 3, and corresponds to the region 50a indicated by the dashed line in FIGS. 1A and 1B. The inner peripheral molding surface 32 is formed as an uneven surface. An uneven surface can be formed by creating height differences on the surface. In this embodiment, the uneven surface is formed by a blasting method in which an abrasive is sprayed onto the surface to form unevenness. Examples of blasting methods include sandblasting and wet blasting in which an abrasive-containing blasting fluid is sprayed onto the surface to form unevenness. Note that the uneven surface may also be formed by a method in which a chemical agent is used to roughen the surface instead of using a blasting method.

[0025] The outer peripheral molding surface 33 is a surface formed on the radially outer side of the lower mold 3, and is formed as a glossy surface. The glossy surface can be formed by cutting.

[0026] 1B, the upper mold 2 has an inner peripheral molding surface 22 and an outer peripheral molding surface 23 that is continuous with the inner peripheral molding surface 22. The inner peripheral molding surface 22 and the outer peripheral molding surface 23 have cross-sectional shapes that are vertically symmetrical to the inner peripheral molding surface 32 and the outer peripheral molding surface 33 of the lower mold 3, except that they do not have the grooves 31, 31 that are provided in the lower mold 3.

[0027] When the upper mold 2 and the lower mold 3 are combined, the inner peripheral molding surface 22 of the upper mold 2 and the inner peripheral molding surface 32 of the lower mold 3 are continuous across the parting surfaces 2a, 3a, as shown in FIG. 1B . That is, the molding die 1 has an uneven surface in an area 50a extending vertically across the parting surfaces 2a, 3a. Similarly, the outer peripheral molding surface 23 of the upper mold 2 and the outer peripheral molding surface 33 of the lower mold 3 are continuous across the parting surfaces 2a, 3a. In the upper mold 2, the inner peripheral molding surface 22 and the outer peripheral molding surface 23 are continuous within the upper mold 2 without straddling the parting surfaces 2a, 3a. Similarly, in the lower mold, the inner peripheral molding surface 32 and the outer peripheral molding surface 33 are continuous within the lower mold 3 without straddling the parting surfaces 2a, 3a.

[0028] Next, a method for manufacturing the molding die 1 will be described. The method for manufacturing the molding die 1 comprises a concave-convex surface processing step and a glossy surface processing step. The concave-convex surface processing step and the glossy surface processing step are performed in the same way on both the upper die 2 and the lower die 3, so the following description will be given taking the case of processing the lower die 3 as an example.

[0029] The uneven surface processing step is a step of processing the inner peripheral molding surface 32 of the lower mold 3 into an uneven surface. On the other hand, the glossy surface processing step is a step of processing the outer peripheral molding surface 33 of the lower mold 3 into a glossy surface. Prior to these steps, the inner peripheral molding surface 32 of the lower mold 3 is machined as shown in FIG. 2. At the same time, a preliminary molding surface 33a is machined on the outer periphery of the lower mold 3. The preliminary molding surface 33a has a flat bottom surface 33a2 that is continuous with the inner peripheral molding surface 32, and a peripheral wall surface 33a1 that rises from the outer periphery of the bottom surface 33a2.

[0030] In the uneven surface processing step, as a preliminary step, a mask is applied to the parting surface 3a of the lower mold 3. Then, by sandblasting, an abrasive is sprayed onto the entire inner peripheral molding surface 32 including the grooves 31 of the lower mold 3 and the entire pre-molding surface 33a. As a result, the entire molding surface of the lower mold 3 is scraped off by the abrasive, and an area 50b (shown by a dashed line) across the entire molding surface is formed into an uneven surface.

[0031] Thereafter, in a glossy surface processing step, the outer periphery of the lower mold 3 is cut to form an outer peripheral molding surface 33, as shown in Figure 3. Figure 3 shows the state during processing when the glossy surface is processed. In the glossy surface processing step, the preliminary molding surface 33a on the outer periphery of the lower mold 3 is cut to form an outer peripheral molding surface 33 that has been made glossy. A boundary portion 35 that marks the boundary between the inner peripheral molding surface 32 and the outer peripheral molding surface 33 (the boundary between the uneven surface and the glossy surface) is located in the radial center of the entire molding surface of the lower mold 3.

[0032] By going through the steps described above, a lower mold 3 is manufactured having an inner peripheral molding surface 32 that is an uneven surface and an outer peripheral molding surface 33 that is a glossy surface. Note that by going through similar steps, an upper mold 2 is manufactured having an inner peripheral molding surface 22 that is an uneven surface and an outer peripheral molding surface 23 that is a glossy surface. In other words, the uneven surface remains on the inner peripheral side of the molding surface of the mold.

[0033] Next, the seal member 50 manufactured by the molding die 1 having the upper die 2 and lower die 3 as described above will be described in detail with reference to FIG. As shown in Fig. 4, the seal member 50 is suitably disposed between the slidable member W1, which is the fixed member side, and the sliding member W2, which moves relatively with respect to the slidable member W1. The seal member 50 has lip portions 51 protruding in all four directions and has a generally X-shaped cross section. The seal member 50 is an annular member made of resin that has low sliding resistance (friction coefficient) with the sliding member W2, and is tough and wear-resistant.

[0034] The seal member 50 has an inner peripheral side surface 52 that comes into sliding contact with the sliding member W2, and an outer peripheral side surface 53 that comes into contact with the slidable member W1. The inner peripheral side surface 52 is a surface that is formed by the inner peripheral molding surfaces 22, 32 (see FIG. 1B) of the molding die 1 (shown by the two-dot chain line in FIG. 4). The inner peripheral side surface 52 spans the overflow portion 55a and extends over the entire upper and lower lip portions 51, 51. The outer peripheral side surface 53 is the remaining surface other than the inner peripheral side surface 52.

[0035] The inner peripheral side surface 52 is entirely formed with a matte texture by the molding die 1. On the other hand, the outer peripheral side surface 53 is formed with a glossy surface by the molding die 1. As a result, the inner peripheral side surface 52 is set to a low-friction surface with a lower friction coefficient than the outer peripheral side surface 53 at boundaries 56, 56 with the outer peripheral side surface 53, and there is a difference in friction coefficient between the inner peripheral side surface 52 and the outer peripheral side surface 53. By providing such a difference in friction coefficient, the inner peripheral side surface 52 of the seal member 50 has slidability with respect to the sliding member W2, and the outer peripheral side surface 53 has adhesion to the slid member W1. The axial direction X1 of the seal member 50 is the same direction as the axial direction (sliding direction) of the sliding member W2.

[0036] Fig. 5 is a cross-sectional view showing a piston pump using the seal member of this embodiment. As shown in Fig. 5, piston pump 10 includes piston 110, which functions as the sliding member described above, and cylinder chamber 102, which functions as the slidable member described above.

[0037] The piston pump 10 is provided in a brake fluid pressure control device mounted on a vehicle. The brake fluid pressure control device controls the brake fluid pressure acting on the wheel brakes, and is connected between a master cylinder chamber (not shown) and the wheel brakes. The brake fluid pressure control device includes a base body 100 serving as a pump body. A solenoid valve and a motor (electric motor), not shown, are attached to the base body 100. One end of a cylinder chamber 102 is open to a side surface 101 of the base body 100. The opening at one end of the cylinder chamber 102 is sealed by a cover member 114. A plurality of flow paths (not shown) are formed within the base body 100, through which brake fluid as a liquid flows.

[0038] The piston pump 10 includes a cylinder chamber 102 , a piston 110 , a seat member 111 , an eccentric cam 112 , a coil spring 113 , and a cover member 114 .

[0039] The cylinder chamber 102 has a stepped cylindrical shape that narrows in steps from the side surface 101 toward the center of the base body 100. The cylinder chamber 102 includes a large diameter portion 104 that opens to the side surface 101, a first medium diameter portion 105 that continues to one end of the large diameter portion 104, a second medium diameter portion 106 that continues to one end of the first medium diameter portion 105, and a small diameter portion 107 that continues to one end of the second medium diameter portion 106.

[0040] A cover member 114 is attached to the large diameter portion 104, and a seat member 111 is attached to the first medium diameter portion 105. The seal member 50 is disposed inside the second medium diameter portion 106. A piston 110 is disposed from the inside of the first medium diameter portion 105 to the inside of the small diameter portion 107.

[0041] The concave inner space of the cover member 114 accommodates a biasing spring 115a and a spherical valve body 115b that constitute the discharge valve 115. The valve body 115b is biased by the biasing spring 115a toward the seat member 111 and is seated in a hole formed in the bottom of one end of the seat member 111. A discharge port 114a communicating with the recessed inner space is formed in the peripheral wall of the cover member 114. Brake fluid is discharged from the piston pump 10 through this discharge port 114a.

[0042] The seat member 111 has a cylindrical shape with a bottom, and defines a pump chamber 118 having a concave inner space. An intake port 117 is formed in the peripheral wall of the seat member 111, and communicates with a space 105a formed inside the first medium diameter portion 105. The space 113a is configured so that brake fluid flows in via an intake valve (not shown) and the intake port 117.

[0043] The pump chamber 118 is a space for increasing the hydraulic pressure of the brake fluid. A coil spring 113 is disposed in the pump chamber 118. The coil spring 113 abuts against one end of a piston 110 disposed in the pump chamber 118, and urges the piston 110 toward an eccentric cam 112 on the other end side. The eccentric cam 112 is attached to an output shaft 121 of an electric motor (not shown).

[0044] The seal member 50 is disposed inside the second medium diameter portion 106 and fitted onto the piston 110 at approximately the middle position. The seal member 50 is sandwiched between the inner peripheral surface of the second medium diameter portion 106 of the cylinder chamber 102 and the outer peripheral surface of the piston 110, and provides a liquid-tight seal between the inner peripheral surface of the second medium diameter portion 106 and the outer peripheral surface of the piston 110. The seal member 50 is positioned between two annular stoppers 126a, 126b fitted onto the inner surface of the second medium diameter portion 106 as shown in FIG. 5.

[0045] In the piston pump 10, the piston 110 reciprocates in the axial direction within the cylinder chamber 102 due to the eccentric cam 112. When the piston 110 moves to the other end side (the cam chamber 120 side), brake fluid is sucked into the pump chamber 118 from the suction port 117, and when the piston 110 moves to the one end side (the pump chamber 118 side), brake fluid is discharged from the pump chamber 118 to the discharge path 108 via the discharge valve 115 and the discharge port 114a.

[0046] In such a piston pump 10, the sealing member 50 ensures sliding of the piston 110 by having its uneven surface slide against the outer peripheral surface of the piston 110, while suppressing movement relative to the cylinder chamber 102 by having its glossy surface abut against the wall surface of the pump chamber 118.

[0047] According to the embodiment described above, a concave-convex surface is formed on the entire molding surface of the molding die 1 in the concave-convex surface processing step, and then a portion of the concave-convex surface is further machined to form a glossy surface in the glossy surface processing step. This allows the concave-convex surface and glossy surface to be formed without applying masking or the like to the molding surface. Furthermore, because the machining in the concave-convex surface processing step and the cutting in the glossy surface processing step are performed on a mold-by-mold basis, machining can be performed regardless of the mold parting position (parting surfaces 2a, 3a). This results in excellent surface quality and improved processability. Furthermore, since the textured surface and the glossy surface can be easily formed, even when a single molding die 1 is used to mold a plurality of pieces, there is no risk of variations occurring, and the seal member 50 can be molded cheaply and easily.

[0048] Furthermore, in the molding die 1, the outer periphery side where the molding surface area is large is machined in the glossy surface machining step, so that the machining is easy to carry out and manufacturing is easy. The seal member 50 can also be suitably used in a piston pump 10 that includes a piston 110 that reciprocates within the cylinder chamber 102. In this case, the sliding of the piston 110 is ensured by the sliding contact of the inner peripheral side surface 52 of the seal member 50, while the movement of the seal member 50 relative to the cylinder chamber 102 can be suppressed by the abutment of the outer peripheral side surface 53 of the seal member 50. In addition to the piston pump 10, the seal member 50 can also be suitably disposed between a slidable member and a sliding member that moves relative to the slidable member. In this case, the uneven surface functions as a sliding surface that makes sliding contact with the sliding member, and the glossy surface functions as a non-sliding surface that abuts against the slidable member. This ensures the sliding of the sliding member through the sliding contact of the uneven surface, while suppressing movement relative to the slidable member through the abutment of the glossy surface. In this way, the surfaces with different surface properties can be appropriately disposed relative to the sliding member and the slidable member, thereby improving the durability of the seal member 50.

[0049] (Second embodiment) Next, a method for manufacturing a mold for molding a seal member according to a second embodiment of the present invention will be described. Fig. 6A is a cross-sectional view showing the molding surface of a molding die manufactured by the method for manufacturing a mold for molding a seal member according to the second embodiment of the present invention, and Fig. 6B is a cross-sectional view showing a seal member molded by the mold for molding a seal member according to the second embodiment of the present invention.

[0050] As shown in FIG. 6A, molding die 1A of this embodiment has upper die 2A and lower die 3A with parting surfaces 2a, 3a that form an oblique parting line that is inclined with respect to axial direction X1. The upper mold 2A has an inner peripheral molding surface 22A and an outer peripheral molding surface 23A that is continuous with the inner peripheral molding surface 22A. On the other hand, the lower mold 3A has an inner peripheral molding surface 32A and an outer peripheral molding surface 33A that is continuous with the inner peripheral molding surface 32A. In other words, the upper mold 2A and the lower mold 3A each have two molding surfaces that are not separated by the parting surfaces 2a, 3a. The inner peripheral molding surface 22A and the outer peripheral molding surface 23A of the upper mold 2A have grooves 31, 31 that face the parting surface 2a.

[0051] As in the first embodiment, the inner peripheral molding surface 22A of the upper mold 2A and the inner peripheral molding surface 32A of the lower mold 3A are formed with uneven surfaces by blasting.

[0052] This molding die 1A is manufactured by a concave-convex surface processing step and a glossy surface processing step, similar to the first embodiment. In the concave-convex surface processing step, inner peripheral molding surfaces 22A, 32A that are concave-convex surfaces are formed on the upper mold 2A and the lower mold 3A. In addition, in the glossy surface processing step, outer peripheral molding surfaces 23A, 33A that are glossy surfaces are formed on the upper mold 2A and the lower mold 3A.

[0053] As shown in Fig. 6B, the sealing member 50A manufactured using the molding die 1A has an inner peripheral side surface 52A and an outer peripheral side surface 53A. The inner peripheral side surface 52A is a surface (shown by a two-dot chain line in Fig. 6B) that is molded by the inner peripheral molding surfaces 22A, 32A (see Fig. 6A) of the molding die 1A. The inner peripheral side surface 52A spans the entire upper and lower lip portions 51, 51, straddling the overflow portion 55a. The outer peripheral side surface 53A is the remaining surface other than the inner peripheral side surface 52A. The outer peripheral side surface 53A also spans the entire upper and lower lip portions 51, 51, straddling the overflow portion 55a.

[0054] Inner peripheral side surface 52A is entirely formed with a matte textured uneven surface by molding die 1A. On the other hand, outer peripheral side surface 53A is formed with a glossy surface by molding die 1A. As a result, inner peripheral side surface 52A is set to a low-friction surface with a lower friction coefficient than outer peripheral side surface 53A at boundaries 56, 56 with outer peripheral side surface 53A, and there is a difference in friction coefficient between inner peripheral side surface 52A and outer peripheral side surface 53A.

[0055] This embodiment also provides the same effects as those of Embodiment 1. That is, an uneven surface can be formed on the entire molding surface of molding die 1A in the uneven surface processing step, and then a glossy surface can be formed by further cutting part of the uneven surface in the glossy surface processing step, so that the uneven surface and glossy surface can be formed without applying masking or the like to the molding surface.

[0056] (Third embodiment) Next, a method for manufacturing a mold for molding a seal member according to a third embodiment of the present invention will be described. Fig. 7A is a cross-sectional view showing the molding surface of a molding die manufactured by the method for manufacturing a mold for molding a seal member according to the third embodiment of the present invention, and Fig. 7B is a cross-sectional view showing a seal member molded by the mold for molding a seal member according to the third embodiment of the present invention.

[0057] 7A has a molding surface with a generally elliptical cross section, with the major axis being the axial direction X1 (sliding direction) and the minor axis being the radial direction of the seal member 50B, which is perpendicular to the axial direction X1. The upper mold 2B and the lower mold 3B are separated by a central parting surface (parting line) 2a, 3a, which is generally in the center in the vertical direction.

[0058] The upper mold 2B has an inner peripheral molding surface 22B and an outer peripheral molding surface 23B that is continuous with the inner peripheral molding surface 22B. On the other hand, the lower mold 3B has an inner peripheral molding surface 32B and an outer peripheral molding surface 33B that is continuous with the inner peripheral molding surface 32B. In other words, the upper mold 2B and the lower mold 3B each have two molding surfaces that are not separated by the parting surfaces 2a, 3a. The inner peripheral molding surface 32B and the outer peripheral molding surface 33B of the lower mold 3B have grooves 31, 31 that face the parting surface 2a.

[0059] As in the first embodiment, the inner peripheral molding surface 22B of the upper mold 2B and the inner peripheral molding surface 32B of the lower mold 3B are formed with uneven surfaces by blasting.

[0060] This molding die 1B is manufactured by a concave-convex surface processing step and a glossy surface processing step, as in the first and second embodiments. In the concave-convex surface processing step, inner peripheral molding surfaces 22B, 32B that are concave-convex surfaces are formed on the upper mold 2B and the lower mold 3B. In addition, in the glossy surface processing step, outer peripheral molding surfaces 23B, 33B that are glossy surfaces are formed on the upper mold 2B and the lower mold 3B.

[0061] As shown in Fig. 7B, sealing member 50B manufactured using molding die 1B has inner peripheral side surface 52B and outer peripheral side surface 53B. Inner peripheral side surface 52B is a surface formed by inner peripheral molding surfaces 22B, 32B (see Fig. 7A) of molding die 1B (shown by a two-dot chain line in Fig. 7B). Inner peripheral side surface 52B extends vertically across overflow portion 55a. Outer peripheral side surface 53B is the remaining surface other than inner peripheral side surface 52B. Outer peripheral side surface 53B also extends vertically across overflow portion 55a.

[0062] The inner peripheral side surface 52B is entirely formed with a matte textured uneven surface by the molding die 1B. On the other hand, the outer peripheral side surface 53B is formed with a glossy surface by the molding die 1B. As a result, the inner peripheral side surface 52B is set to a low-friction surface with a lower friction coefficient than the outer peripheral side surface 53B at boundaries 56, 56 with the outer peripheral side surface 53B, and there is a difference in friction coefficient between the inner peripheral side surface 52B and the outer peripheral side surface 53B.

[0063] This embodiment also provides the same effects as those of Embodiment 1. That is, an uneven surface can be formed on the entire molding surface of molding die 1B in the uneven surface processing step, and then a glossy surface can be formed by further cutting part of the uneven surface in the glossy surface processing step, so that the uneven surface and glossy surface can be formed without applying masking or the like to the molding surface.

[0064] (Fourth embodiment) Next, a method for manufacturing a mold for molding a seal member according to a fourth embodiment of the present invention will be described. Fig. 8A is a cross-sectional view showing the molding surface of a molding die manufactured by the method for manufacturing a mold for molding a seal member according to the fourth embodiment of the present invention, and Fig. 8B is a cross-sectional view showing a seal member molded by the mold for molding a seal member according to the fourth embodiment of the present invention.

[0065] The molding die 1C shown in Fig. 8A has a molding surface with a cross section that is approximately D-shaped. Upper die 2C and lower die 3C have parting surfaces 2a and 3a that form an oblique parting line that is inclined with respect to axial direction X1.

[0066] The upper mold 2C has an inner peripheral molding surface 22C and an outer peripheral molding surface 23C that is continuous with the inner peripheral molding surface 22C. On the other hand, the lower mold 3C has an inner peripheral molding surface 32C and an outer peripheral molding surface 33C that is continuous with the inner peripheral molding surface 32C. In other words, the upper mold 2C and the lower mold 3C each have two molding surfaces that are not separated by the parting surfaces 2a, 3a. The inner peripheral molding surface 22C and the outer peripheral molding surface 23C of the upper mold 2C have grooves 31, 31 that face the parting surface 2a.

[0067] As in the first embodiment, the inner peripheral molding surface 22C of the upper mold 2C and the inner peripheral molding surface 32C of the lower mold 3C are formed with uneven surfaces by blasting.

[0068] This molding die 1C is manufactured by a concave-convex surface processing step and a glossy surface processing step, similar to the first embodiment. The concave-convex surface processing step forms concave-convex inner molding surfaces 22C, 32C on the upper mold 2C and the lower mold 3C. The glossy surface processing step forms glossy outer molding surfaces 23C, 33C on the upper mold 2C and the lower mold 3C.

[0069] As shown in Fig. 8B, the sealing member 50C manufactured using the molding die 1C has an inner peripheral side surface 52C and an outer peripheral side surface 53C. The inner peripheral side surface 52C is a surface formed by the inner peripheral molding surfaces 22C, 32C (see Fig. 8A) of the molding die 1C (shown by a two-dot chain line in Fig. 8B). The inner peripheral side surface 52C extends vertically across the overflow portion 55a. A lip portion 51C that protrudes radially inward is provided at the vertical center of the inner peripheral side surface 52C. The outer peripheral side surface 53C is the remaining surface other than the inner peripheral side surface 52C. The outer peripheral side surface 53C also extends vertically across the overflow portion 55a.

[0070] Inner peripheral side surface 52C is entirely formed with a matte textured uneven surface by molding die 1C. On the other hand, outer peripheral side surface 53C is formed with a glossy surface by molding die 1C. As a result, inner peripheral side surface 52C is set to a low-friction surface with a lower friction coefficient than outer peripheral side surface 53C at boundaries 56, 56 with outer peripheral side surface 53C, and there is a difference in friction coefficient between inner peripheral side surface 52C and outer peripheral side surface 53C.

[0071] This embodiment also provides the same effects as those of Embodiment 1. That is, an uneven surface is formed on the entire molding surface of molding die 1C in the uneven surface processing step, and then a glossy surface is formed by further cutting part of the uneven surface in the glossy surface processing step, so that the uneven surface and the glossy surface can be formed without applying masking or the like to the molding surface.

[0072] (Fifth embodiment) Next, a method for manufacturing a mold for molding a seal member according to a fifth embodiment of the present invention will be described. Fig. 9A is a cross-sectional view showing the molding surface of a molding die manufactured by the method for manufacturing a mold for molding a seal member according to the fifth embodiment of the present invention, and Fig. 9B is a cross-sectional view showing a seal member molded by the mold for molding a seal member according to the fifth embodiment of the present invention.

[0073] 9A has a molding surface with a generally rectangular cross section. An upper mold 2C and a lower mold 3D are separated by a central parting line 2a, 3a, which is located roughly in the center in the vertical direction.

[0074] The upper mold 2D has an inner peripheral molding surface 22D and an outer peripheral molding surface 23D that is continuous with the inner peripheral molding surface 22D. On the other hand, the lower mold 3D has an inner peripheral molding surface 32D and an outer peripheral molding surface 33D that is continuous with the inner peripheral molding surface 32D. In other words, the upper mold 2D and the lower mold 3D each have two molding surfaces that are not separated by the parting surfaces 2a, 3a. The inner peripheral molding surface 22D and the outer peripheral molding surface 23D of the upper mold 2D have grooves 31, 31 that face the parting surface 2a.

[0075] As in the first embodiment, the inner peripheral molding surface 22D of the upper mold 2D and the inner peripheral molding surface 32D of the lower mold 3D are formed with uneven surfaces by blasting.

[0076] This molding die 1D is manufactured by a concave-convex surface processing step and a glossy surface processing step, similar to the first embodiment. The concave-convex surface processing step forms concave-convex inner molding surfaces 22D, 32D on the upper mold 2D and the lower mold 3D, respectively. The glossy surface processing step forms glossy outer molding surfaces 23D, 33D on the upper mold 2D and the lower mold 3D, respectively.

[0077] As shown in Fig. 9B, sealing member 50D manufactured using molding die 1D has inner peripheral side surface 52D and outer peripheral side surface 53D. Inner peripheral side surface 52D is a surface formed by inner peripheral molding surfaces 22D, 32D (see Fig. 8A) of molding die 1D (shown by a two-dot chain line in Fig. 8B). Inner peripheral side surface 52D extends vertically across overflow portion 55a. Outer peripheral side surface 53D is the remaining surface other than inner peripheral side surface 52D. Outer peripheral side surface 53D also extends vertically across overflow portion 55a.

[0078] Inner peripheral side surface 52D is entirely formed with a matte textured uneven surface by molding die 1D. On the other hand, outer peripheral side surface 53D is formed with a glossy surface by molding die 1D. As a result, inner peripheral side surface 52D is set to a low-friction surface with a lower friction coefficient than outer peripheral side surface 53D at boundaries 56, 56 with outer peripheral side surface 53D, and there is a difference in friction coefficient between inner peripheral side surface 52D and outer peripheral side surface 53D.

[0079] This embodiment also provides the same effects as those of Embodiment 1. That is, an uneven surface can be formed on the entire molding surface of molding die 1D in the uneven surface processing step, and then a glossy surface can be formed by further cutting part of the uneven surface in the glossy surface processing step, so that the uneven surface and glossy surface can be formed without applying masking or the like to the molding surface.

[0080] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be modified as appropriate within the scope of the invention. In the third and fifth embodiments, the molding dies 1B, 1D are configured with centrally divided parting surfaces 2a, 3a, but this is not limited to this and they may be configured with parting surfaces that form diagonal parting lines. Furthermore, in the fourth embodiment, the molding die 1C is configured with parting surfaces 2a, 3a that form a diagonal parting line, but this is not limitative and the molding die 1C may be configured with a centrally parted parting surface. Furthermore, in each of the above embodiments, the uneven surface processing process and the glossy surface processing process are performed in the same manner on both the upper mold 2, 2A to 2D and the lower mold 3, 3A to 3D, but this is not limited to this and they may be performed on either one of them. Furthermore, in each of the above embodiments, the glossy surface processing step is performed after the uneven surface processing step, but this is not limited to this, and the uneven surface processing step may also be performed after the glossy surface processing step. [Explanation of symbols]

[0081] 1 Molding mold 1A~1D mold 2 Upper mold (molding mold) 2a Parting surface (mold splitting surface) 2A~2D Upper mold (molding mold) 3 Lower mold (molding mold) 3a Parting surface (mold splitting surface) 3A~3D Lower mold (molding mold) 10 Piston pump 22 Inner molding surface 22A~22D Inner molding surface 33 Peripheral molding surface 33A~33D Outer molding surface 50 sealing material 50A~50D Sealing material 102 Cylinder chamber (sliding member) 110 Piston (sliding member)

Claims

1. A method for manufacturing a molding die for molding an annular seal member having an inner peripheral side surface and an outer peripheral side surface, comprising: The molding die includes a pair of molding dies separated by a parting surface, a step of performing cutting processing on at least one of the pair of molds to form a first molding surface corresponding to at least one of the inner peripheral side surface and the outer peripheral side surface, and to form a preliminary molding surface which is a precursor to a second molding surface corresponding to the other of the inner peripheral side surface and the outer peripheral side surface; a concave-convex surface processing step of processing the cut first molding surface into a concave-convex surface; and a glossy surface processing step of cutting the preform surface adjacent to the uneven surface processed in the uneven surface processing step into a glossy surface.

2. 2. The method for manufacturing a mold for molding a sealing member according to claim 1, wherein the glossy surface processing step is performed after the uneven surface processing step, and a portion of the uneven surface processed in the uneven surface processing step is machined into a glossy surface.

3. 3. The method for manufacturing a mold for molding a seal member according to claim 1, wherein the uneven surface is left on the inner periphery of the molding surface of the mold.

4. 4. The method for manufacturing a mold for molding a sealing member according to claim 1, wherein the uneven surface processing step includes processing the uneven surface by a blasting method.

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